Please make a donation to support Gunter's Space Page.
Thank you very much for visiting Gunter's Space Page. I hope that this site is useful and informative for you.
If you appreciate the information provided on this site, please consider supporting my work by making a simple and secure donation via PayPal. Please help to run the website and keep everything free of charge. Thank you very much.

ESRO 2A, 2B (Iris 1, 2)

ESRO 2 (European Space Research Organisation), Iris (International Radiation
Investigation Satellite) was a 75 kg spin-stabilized spacecraft On the launch of ESRO 2A,
the third stage vehicle failed and the spacecraft did not achieve orbit. ESRO 2B was
launched on 16 May 1968, into a near polar orbit. The main objective of ESRO 2 was to
conduct a study of solar astronomy and cosmic rays. The ESRO 2 experiments had their
counterparts in the NASA-OSO series. The purpose of the spacecraft was to provide
continuity to the solar radiation observations carried out by OSO D
launched 18 October 1967. The particle experiments were designed to continue similar
measurements carried out by the Ariel 1 (UK 1) satellite.

Experiments on board were:

Monitor of Energetic Particle Flux

Solar and Van Allen Belt Protons

Solar and Galactic Alpha Particles and Protons

Primary Cosmic Ray Electrons

Hard Solar X-rays

Soft Solar X-rays

Flux and Energy Spectra of Solar and Galactic Cosmic Ray Particles

The satellite had a spin rate of about 40 rpm and had completed 16,282 orbits of the
earth before reentry on 8 May 1971, shortly after 0300 UT. No playback data has been
available since 10 December 1968, following a mechanical failure of the onboard tape
recorder. The failure reduced the data flow by about 80 percent, although a combination of
Estrack (ESRO) and STADAN (NASA) tracking stations were used.